The invention relates to an electrical device, particularly to a device for detecting objects, for example, to a locating device and thereby particularly to a device comprising at least one ultra wideband (UWB) sensor.
In contrast to conventional narrow-band radio communication services, UWB sensor devices use a very large frequency range with, however, a relatively low power spectrum. The use of this large frequency range results in frequency ranges being covered, which are already used by existing radio communication services. Due to the low power spectrum of the UWB sensor devices and the narrow-band nature of the receivers of the existing radio communication services, the interference potential of the UWB sensor devices is very small. Said interference potential does, however, depend on the distance between the UWB sensor device and the narrow-band receiver. This interference can thereby be regarded as noise interference by the radio communication services. When the distance between said UWB sensor device and said narrow-band receiver is small, the interference potential can, however, exceed an admissible limit, and the transmitter of said UWB sensor device must be turned off to avoid an interference of the narrow-band device.
The interference potential of active narrow-band devices on UWB sensor devices is in such cases considerably larger because the total energy of the narrow-band transmitter is received by the wideband receiver of the UWB sensor device. Decreasing the distance between the two devices leads to said UWB sensor device not being able to receive its own signals and consequently to said UWB device no longer being able to operate and to it having to react to the interference. UWB devices in contrast to radio communication services do not, however, enjoy any protection from interference.
Suitable signal sources of a UWB sensor device are e.g.:                Pulse trains        Pseudo-noise (PN) sequences        Frequency modulated continuous wave (FMCW)        Stepped frequency continuous wave (SFCW)        Frequency-shift system        
The generation of pulse trains can be made by diodes (e.g. SR diode), a transistor or a transistor circuit. Pseudo-noise sequences can be generated by feedback shift registers (e.g. discrete design using gates, FPGA implementation, digital chip) or by a lookup table, respectively memory. The methods for signal generation correspond to the technical field.
The FMCW and frequency-shift method is an established method in the field of radar technology. In this case, a modulated signal is superimposed on a carrier frequency. This modulated signal simultaneously represents the measuring signal and is recovered after reception with the aid of a mixer.
It is the aim of the invention to be able to operate locating devices in the presence of radio communication services and to keep the disturbing electromagnetic interactions between said devices and services to a minimum or avoid them altogether. Within the scope of the invention, external high frequency signals and corresponding radio communication services, as, for example, mobile radio systems, are considered to be radio communication services.